He said: “The train went mad and everyone was clapping. When I got off at my stop, they were all banging on the windows. The train driver even got off and shook my hand.

“Because of this video, everyone wants me to go and sing at my local The Taproom.”

William said: "I can't believe it, I am literally speechless and I am never usually stuck for words.

"It was a works night out and I got the train with my pal as I didn't want to spend money on a taxi home.

"There was a few of us on the train and a girl noticed me from singing in the pub. The group of guys started egging me on, trying to get me to sing, so I thought I would just give it a go.

"The train went mad and everyone was clapping - when I got off at my stop, Hamilton West, they were all banging on the windows and the train driver even got off and shook my hand.

"I was getting invites to parties and everything.

"When I woke up at 11am this morning I had over 200 Facebook notifications and I thought 'I've not even got that many friends'.

"It has just been crazy and I am really glad I am getting the exposure. I didn't even know I was being filmed, but I really want to thank the guy who filmed it as it's got me so much exposures and so many views online.

"I'd love to be a full time singer, I do gigs in and around Hamilton - and because of this video, everyone wants me to go and sing at my local, The Taproom tonight.

"I think I have sang Nessun Dorma more than Pavarotti - when I ask DJ's in pubs if I can sing it they give me funny looks.

Folk ask me all the time what key I am in - I've not a clue. I am not trained and have never had a vocal coach."

Scott Thompson, owner of a cleaning firm was on the train with a group of pals and decided to catch William's big moment on camera.

He said: "At the end of out friend's 40th birthday we got the last train home from Glasgow Central to Larkhall whilst trying to sing Frozen's Let It Go this guy was sitting very quite and we asked him to join us singing he refused at first but after a bit of banter he silenced the whole train - it was absolutely priceless.

"You know what the last train home is normally like - but this guy gave us our very own Subo moment."